The present invention relates to a transport device and a transport method for transporting a fragile object.
In the field of producing semiconductor devices, semiconductor chips with integrated circuits are produced, for example. Herein, fragile objects like for example wafers, glass panels, solar modules etc. are transported. Because of the fragility of the objects, high caution is required when handling the objects to prevent damaging, like breaking, of the fragile objects.
For transporting a fragile object to a predefined position during a production process, a linear motor can be used, which operates according to an ‘inverted motor principle’. ‘Inverted motor principle’ means that compared to a normal situation of a linear motor the opposite component moves, namely the magnet plate (secondary part of the motor) moves whereas in a normal linear motor, the coil (primary part of the motor) moves.
Such a linear motor operating according to an inverted motor principle moves a carrier with the fragile object thereon along a movement path. For this purpose, coils of the linear motor are activated or deactivated in succession to move the carrier along the movement path or to stop the carrier at the predefined or desired position on the movement path. The linear motor operating according to an inverted motor principle and the coils are also named LMS system hereinafter.
In current LMS systems, for starting a movement of a carrier, acceleration is applied instantaneously to a carrier positioned on a coil. In a similar way, when stopping a carrier, deceleration is applied instantaneously to the carrier. This results in an abrupt start or stopping of the movement of the carrier. Thus, the object carried by such a carrier in the LMS system can start to vibrate because of the abrupt start or stopping of the movement. This can lead to a damage of the objects.